Economic-Based Optimization

Principles of Chemical Reactor Analysis and Design, Second Edition. By Uzi Mann Copyright 2009 John Wiley Sons, Inc. 

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Forbes, F. T. Marlin and J. MacGregor. Model Selection Criteria for Economics-Based Optimizing Control. Comput Chem Eng 18 497-510 (1994). 

The example below illustrates an economic-based optimization procedure. 

Figure 8.9. Pareto optimal cm ve /econ versus /exergy Legend E economic-based optimal design X exergy-based optimal design Q optimal design based equally on economic performance and exergy efficiency Remarks each point of the curve represents an optimal solution in terms of the design variables [m-cat, Q, a

Kurus D (2006) Simulation-based optimization model for supply chain planning of commodities in the chemical industry Technical University of Berlin Lababidi HMS, Ahmed MA, Alatiqi IM, Al-Enzi AF (2004) Optimizing the Supply Chain of a Petrochemical Company under Uncertain Operating and Economic Conditions. Industrial Engineering Chemistry Research 43 63-73 Labys WC (1973) Dynamic Commodity Models Specification, Estimation and Simulation, Lexington Books, Lexington... 

In this chapter we have advocated the use of online model-based optimization for the automatic control of SMB plants. This approach has the advantage that the process is automatically operated at its economic optimum while meeting all relevant constraints on purities and flow rates. Application to a pilot-plant-scale reactive SMB process for glucose isomerization showed that implementation at a real plant is feasible - the requirements for additional hardware are moderate (a high-level PC and online concentration measurements in the recycle line). The experiments confirmed the excellent properties of the proposed control scheme. The scheme is extremely versatile, and the cost function and constraints can easily be adapted to any specific separation task. 

The economic-hased optimization may be based on other criteria than those discussed in Section 10.1. In some cases, the production rate is specified, and the value of the product is fixed. In such cases, we would like to minimize the total operating cost. This is illustrated in the example below. 

Insight into the economics of limited excursions from the optimized base case... 

The target composition of the undesirable species in each MSA is assigned by the designer based on the specific circumstances of the application. The nature of such circumstances may be physical (e.g., maximum solubility of the pollutant in the MSA), technical (e.g., to avoid excessive corrosion, viscosity or fouling), environmental (e.g., to comply with environmental regulations), safety (e.g., to stay away from flammability limits), or economic (e.g., to optimize the cost of subsequent regeneration of the MSA). 

This reaction has an economic potential of 40.05 million per year. An advantage of the optimization-based approach to synthesizing EARs is its ability to generate... 

The initial aim of the procedure is to generate a reasonable base case design that can be used for preliminary economic evaluation of the process. This can subsequently be optimized and/or compared with any process alternatives that are identified. The complete process is always considered at each decision level, but additional fine detail is added to the structure of the flowsheet at any stage. Established heuristics and equipment selection procedures are used together with new process synthesis insights to guide each flowsheet decision. 

The purification of value-added pharmaceuticals in the past required multiple chromatographic steps for batch purification processes. The design and optimization of these processes were often cumbersome and the operations were fundamentally complex. Individual batch processes requires optimization between chromatographic efficiency and enantioselectivity, which results in major economic ramifications. An additional problem was the extremely short time for development of the purification process. Commercial constraints demand that the time interval between non-optimized laboratory bench purification and the first process-scale production for clinical trials are kept to a minimum. Therefore, rapid process design and optimization methods based on computer aided simulation of an SMB process will assist at this stage. 

The SimuSolv optimize function can be used for minimization of a user defined cost expression. However, at this early stage of process development, no attempt was made to determine parameters for an economic optimum. Instead, many simulations were run to determine parameter sensitivities and malce comparisons of various possibilities which satisfied a necessary objective of reaching the desired low level of residual monomer. Attention was given to minimizing total finishing time, the amount of initiator required and residual initiator level at the end of the finishing step. Based on simulation results for... 

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